The history and present state of discoveries relating to vision, light, and colours / By Joseph Priestley.

  • Priestley, Joseph, 1733-1804.
Date:
1772
Catalogue details

Licence: Public Domain Mark

Credit: The history and present state of discoveries relating to vision, light, and colours / By Joseph Priestley. Source: Wellcome Collection.

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    to the fun, obferved that this part grew hotter than the white, but was not fo hot as the black part. He alfo obferves that rooms hung with black are not only darker, than they would otherwife be, but warmer too j and he knew feveral perfons, who found great inconvenience from rooms hung with black. As another proof of his hypothefis, he informs us that a Virtuofo, of unfufpedted credit, acquainted him, that, in a hot climate, he had feen eggs well roafted in a fhort time, by firft blacking the {hells, and then expof ng them to the fun. * Mr. Boyle obferved a manifeft difference in fome kinds of co¬ loured bodies viewed by day light, and afterwards by the light of the moon. Yellow paper appeared much fainter by moon light than in the day, inclining to a pale ftraw colour. Red paper was but little changed. It only reflected the light more ftrongly than the other colours. A fair deep green, looked upon by itfelf, feemed to be of a dark blue; but viewed together with a dark blue appeared greenilh, and compared with yellow appeared more blue than at firft. The blue looked more like a deep purple than it had done in the day light. The purple feemed very little altered. Laftly, the red, compared with the yellow, made the latter appear almoft like brown cap paper, •f* An obfervation of M. Homberg, concerning the intenfity of different kinds of light, whereby fome more eafily pervade fe- mi-tranfparent fubftances than others, is worth mentioning. He fhut himfelf up in a room, into which no light could be ad¬ mitted, but through one aperture, which was clofed with a piece of glafs, at firft quite rough, and nearly opaque, through which he could perceive the general fhape of objedts, but not . f Boyle’s Works, p. 36. + lb. p. 58. U their